Section 51 of the Constitution defines those areas in which the Commonwealth Parliament, subject to the Constitution, has power to make laws for the peace, order, and good government of the Commonwealth. Specifically, s51 (xxxviii) states:

'The exercise within the Commonwealth, at the request or with the concurrence of the Parliaments of all the states directly concerned, of any power which can at the establishment of this Constitution be exercised only by the Parliament of the United Kingdom or by the Federal Council of Australasia.'S51 (xxxviii) is important for the discussion in this paper because it allows the Commonwealth Parliament to assume any power that was previously exercised only by the Parliament of the United Kingdom or by the Federal Council of Australasia[13] at the establishment of the Constitution.

The power can, however, be exercised only at the request or with the concurrence of the Parliaments of all the States directly concerned. The power is also expressed to be subject to the Constitution, so any law made pursuant to it which conflicts with the Constitution is invalid.[14]

To date, the Parliament of the Commonwealth of Australia has on three occasions passed Acts requesting and consenting to the enactment by the Parliament of the United Kingdom of Acts extending to Australia. The Acts of the Parliaments of the Commonwealth and of the United Kingdom, respectively, are as follows: [15]

Australia

United Kingdom

Australia (Request and Consent) Act 1985 Australia Act 1986Christmas Island (Request and Consent) Act 1957 Christmas Island Act, 1958Cocos (Keeling) Islands (Request and Consent) Act 1954 Cocos Islands Act, 1955Clearly, these three Acts have met all the necessary requirements and, in themselves, do not conflict with s51 (xxxviii) of The Constitution. Specifically, the High Court's decision in Port MacDonnell Professional Fishermen's Association Inc v South Australia (1989) 168 CLR 340 has put at rest any doubts as to the validity of the Australia Act 1986 (Cth). In the unanimous opinion of the court, s 51(xxxviii) of the Constitution should be given a broad interpretation reflecting its 'national purpose of a fundamental kind', which is that of 'plugging gaps which might otherwise exist in the overall plenitude of the legislative powers exercisable by the Commonwealth and State parliaments under the Constitution': 168 CLR at 378, 379.[16]